Dinohippus

Dinohippus
Temporal range: Late Miocene–Late Pliocene
Dinohippus leidyanus skeleton
Scientific classification
Kingdom:Animalia
Phylum:Chordata
Class:Mammalia
Order:Perissodactyla
Family:Equidae
Subfamily:Equinae
Tribe:Equini
Genus:†Dinohippus
Quinn, 1955
Species
  • Dinohippus interpolatus (Cope, 1893)
  • Dinohippus osborni (Frick, 1924)
  • Dinohippus edensis (Frick, 1924)
  • Dinohippus leidyanus (Osborn, 1918) (type)

Dinohippus (Greek: "Terrible horse") is an extinct herbivorous mammal belonging to the tribe Equini of the subfamily Equinae, which was endemic to North America from the late Hemphillian stage of the Miocene through the Zanclean stage of the Pliocene (10.3—3.6 mya) and in existence for approximately 6.7 million years.[1][2]

Taxonomy

Skull

Dinohippus was erected by Quinn (1955) for "Pliohippus" leidyanus Osborn, 1918.[3] Other species assigned to this genus include D. interpolatus, D. osborni, and D. edensis.[4] Quinn (1955) referred "Pliohippus" mexicanus to Dinohippus.

It was the most common horse in North America and like Equus, Dinohippus did not have a dished face. It has a distinctive passive "stay apparatus," formed by bones and tendons, to help it conserve energy while standing for long periods. Dinohippus is the first horse to show a rudimentary form of this character, providing additional evidence of the close relationship between Dinohippus and Equus.[5] Dinohippus was originally thought to be a monodactyl horse, but a 1981 fossil find in Nebraska shows that some were tridactyl.[6]

Morphology

Three specimens were examined for body mass by M. Mendoza, C. M. Janis, and P. Palmqvist as well as M. T. Alberdi, J. L. Prado, and E. Ortiz-Jaureguizar.[7][8]

  • Specimen 1: 567.7 kg (1251 lbs)
  • Specimen 2: 536.5 kg (1182.7 lbs)
  • Specimen 3: 224.0 kg (493.8 lbs)

Fossil distribution

Fossil distribution is widespread throughout North America with more than 30 sites from Florida to Alberta, Canada to Central Mexico.

Species

Dinohippus interpolatus

Foot bones

Dinohippus interpolatus (synonymized with Pliohippus bakeri), D. leardi, D. leidyanus (syn. Pliohippus edensis, Pliohippus osborni)

  • Taxonomy: Hippidium interpolatum was named by Cope (1893) and said originally to have been placed in. Its type locality is Goodnight Bed Formation. Hippidium interpolatum was a grazing and browsing animal.
  • Morphology: One specimen was examined by M. Mendoza, C. M. Janis, and P. Palmqvist. The body mass was estimated to be 119.7 kg (263.8 lbs).[9]

Mendoza et al. (2006:99) state that D. leidyanus had a body mass ~200 kg.

Sister taxa

Astrohippus, Calippus, Equus, Hippidion, Pliohippus, Protohippus (syn. Eoequus)

References

  1. ↑ Paleobiology Database: Dinohippus basic info.
  2. ↑ Bruce J. MacFadden: Cenozoic Mammalian Herbivores from the Americas: Reconstructing Ancient Diets and Terrestrial Communities. Annual Review of Ecology and Systematics, Vol. 31, (2000), pp. 33-59
  3. ↑ J. H. Quinn. 1955. Miocene Equidae of the Texas gulf coastal plain. University of Texas, Bureau of Economic Geology
  4. ↑ B. J. MacFadden. 1998. Equidae. In C. M. Janis, K. M. Scott, and L. L. Jacobs (eds.), Evolution of Tertiary Mammals of North America 1:537-559
  5. ↑ Florida Museum of Natural History
  6. ↑ Horse Ecology
  7. ↑ M. Mendoza, C. M. Janis, and P. Palmqvist. 2006. Estimating the body mass of extinct ungulates: a study on the use of multiple regression. Journal of Zoology
  8. ↑ M. T. Alberdi, J. L. Prado, and E. Ortiz-Jaureguizar. 1995. Patterns of body size changes in fossil and living Equini (Perissodactyla). Biological Journal of the Linnean Society
  9. ↑ M. Mendoza, C. M. Janis, and P. Palmqvist. 2006. Estimating the body mass of extinct ungulates: a study on the use of multiple regression. Journal of Zoology
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